Smartphones, digital media use, and sleep in young adolescents

The purpose of this study was to examine the association between smartphone ownership and usage behaviors and sleep duration and quality among adolescents aged 11 to 13 years, and whether these associations differed by sex.

We analyzed data from 1510 participants in the 2024 Life in Media Survey (LIMS), an online cross-sectional survey of 11- to 13-year-olds in Florida. Logistic regression models adjusted for appropriate confounders assessed associations between smartphone ownership and 6 usage behaviors, including device location at night; in-bed usage; evening usage time; online posting; notifications; and exposure cyberbullying, and the outcomes of sleep duration and trouble sleeping. Sex-stratified analyses were conducted to assess for effect modification.

Smartphone ownership was associated with lower odds of insufficient sleep and trouble sleeping; however, several usage behaviors were strongly linked to poorer sleep. Keeping a smartphone in hand/in bed, using it in bed, posting publicly online, spending more than 2 hours on the device in the evening, and experiencing cyberbullying were each associated with increased odds of insufficient sleep duration and trouble sleeping. Using the phone in bed showed the strongest associations (aORs up to 13 for trouble sleeping). Cyberbullying consistently predicted all adverse sleep outcomes. Sex-stratified results showed variation in some associations.

In early adolescence, how smartphones are used, rather than merely owning one, has substantial implications for sleep. Behaviors such as nighttime proximity, in-bed use, late‑evening screen time, and exposure to online stressors were most detrimental. Promoting healthier bedtime practices and reducing negative online experiences may improve sleep in this age group.